The Vox website posted a copy of a draft of a new rule that it said the administration was reviewing. The rule would undermine coverage for one of the 10 essential health benefits covered by President Barack Obama’s signature piece of domestic legislation, which Republicans have vowed to repeal and replace.

The U.S. Department of Health and Human Services declined to comment and spokeswoman Alleigh Marre said it does not “comment on alleged drafts of documents.” The White House did not immediately respond to a request for comment.

Under the 2010 Affordable Care Act, often called Obamacare, employers are required to provide health insurance that covers birth control, except for religious houses of worship, which are exempt. Some owners of private businesses also obtained exemptions after the Supreme Court ruled in 2014 that they could object to the rule on religious grounds.

Republicans do not have enough seats in the U.S. Senate to fully repeal Obamacare and as a result, the Republican strategy for rolling back the law includes stopping implementation of new health regulations and creating new administrative rules that undermine parts of the existing law.

Planned Parenthood, the American Civil Liberties Union and other healthcare groups criticized the proposed rule and said it would make it harder for millions of Americans to access the healthcare they need. The ACLU threatened to challenge the administration in court if the rule becomes finalized.

“Any rule that allows employers to deny contraceptive coverage to their employees is an attempt at allowing religion to be used as a license to discriminate,” the ACLU said in a statement.